1. Technical Field
The present invention relates to information display devices for superimposing information for display on time-sequentially taken images and display the information, and more particularly to a technique that can suppress an adverse effect to a display screen when a reception condition of transmission from an information source is unstable and thereby improve readability.
2. Background Art
Patent Literature 1 discloses an imaging device which transmits information by means of optical space transmission, and thereby presents information relating to commercial products, exhibits, and the like such that the information is superimposed on taken images and displayed. According to Patent Literature 1, an information source which is provided together with store shelves for commercial products lined at a store front, an advertising board on the street, or the like, transmits presentation information that suits the commercial products or the advertising board by changing brightness. Meanwhile, an imaging device time-sequentially takes images, extracts presentation information for each image region based on change in brightness of the image region, and superimposes the extracted presentation information on the taken images and display the presentation information. Accordingly, relationship between a target for presentation information and the presentation information can be clarified, thereby preventing the information from being conveyed erroneously.
At this time, in the imaging device of Patent Literature 1, when a great number of light sources for transmitting presentation information exist within a viewing angle and extracted information exceeds an allowable amount, readability can be deteriorated significantly. Thus, in such a case, special consideration and the like needs to be given to selection of information and display style.
Patent Literature 2 discloses an information display device that can solve such problems. According to Patent Literature 2, based on data representing a size and a shape of an information source and an area on an image, a distance to the information source is calculated, and in accordance with the calculated distance, a size of a speech bubble and a character size are adjusted, thereby improving readability.